Devices and related methods for collection and transfer of a biological sample fluid (such as blood) have been widely used for a variety of applications, such as analyte-detection, sensing, forensic and diagnostic applications, genome sequencing, and the like. In some applications, a quantitative measurement is desired, such as measuring a concentration of a drug metabolite in the blood, a titer of a virus in a sample, a level of mRNA in a sample and the like. To achieve accurate results for these applications, preserving the structural and functional integrity of the biomolecules present in a biological sample fluid is a primary requirement. A method for preserving integrity of the sample is to store the sample on a stabilizing substrate or a membrane. Measurement of the volume of a sample is also required to achieve accurate results for different quantitative analyses.
The most widely used method of collecting blood sample is by venipuncture, which requires sterile equipment, collection tubes and a trained phlebotomist for drawing the blood sample. An alternate method is skin piercing such as finger stick using a lancet. After piercing, a suitable device and a method is required for collection and/or transfer of the blood sample to a storage substrate or membrane. For these devices, it is necessary to ensure that the correct amount of blood is collected, the blood sample is completely transferred to a substrate, the blood is transferred to a correct location on a substrate, and the blood is applied evenly to a substrate. Application of a sample to a substrate may be achieved by using a capillary for collection followed by sample transfer to the substrate. However, the transfer may not occur completely if a gap exists between the capillary and the membrane. Further, the sample may not be applied evenly if the placement of the capillary is not accurate relative to the substrate or the flow rate of the sample exiting the capillary is controlled appropriately. Therefore, a skilled person is required for careful handling of the device and for collection and transfer of the blood sample.
Devices and methods that allow a person with an average skill to quickly collect and transfer a specific and consistent amount of sample to a correct location on a substrate with an even distribution are highly desirable. The devices and methods may further facilitate an automated sample analysis by applying an accurate amount of sample at a desired position on the substrate.